Electrode for electrolytic condensers



Nov; 21, 1961 B, BRENNAN Re. 25,084

ELECTRODE FOR ELECTROLYTIC CONDENSERS Original Filed Sept. 25, 1946 4Sheets-Sheet 1 INVENTOR. JOSEPH B-BEE/VNA/V A TTOENEYS Nov. 21, 1961 J.B. BRENNAN ELECTRODE FOR ELECTROLYTIC CONDENSERS 4 Sheets-Sheet 2Original Filed Sept. 25 1946 INVENTOR. JOSEPH B .B/PF/V/VA/V ATTORNEYSNov. 21, 1961 J. B. BRENNAN 25,084

ELECTRODE'FOR ELECTROLYTIC CONDENSERS Original Filed Sept. 25, 1946 4Sheets-Shet s Fig-13 INVENTOR. OSEPH .B- BEEN/VAN ATTOiF/VEYS Nov. 21,1961 J;' B. BRENNAN ELECTRODE FOR ELECTROLYTIC CONDENSERS 4 Sheets-Sheet4 Original Filed Sept. 25, 1946 INVENTOR. JOSEPH B-BPE/VNAN ATTORNEYSUnited States Patent Ollice Re. 25,984 Reissued Nov. 21, 1961 25,084ELECTRODE FOR ELECTROLYTIC CONDENSERS Joseph B. Brennan, Cleveland,Ohio, assignor to Everett D. McCurdy, trustee Original No. 2,578,667,dated Dec. 18, 1951, Ser. No. 699,108, Sept. 25, 1946. Application forreissue Feb. 20, 1957, Ser. No. 641,791. This application is acontinuation of Ser. No. 326,807, Dec. 18, 1952 4 Claims. (Cl. 317-230)Matter enclosed in heavy brackets appears in the originalpatent butforms no part of this reissue specification; matter printed in italicsindicates the additions made by reissue.

and elficient electrode and separator assemblies for such electrolyticdevices; to provide etficient electrodes of high capacity which can bemanufactured economically and to provide efficient and economicalmethods for making such electrodes.

As described in detail in my Patent No. 2,104,018, electrodes havingsurfaces composed of cohering particles of film-forming metal such asproduced by a spraydepositing operation are highly advantageous in thatthe porous structure or layer made up of the cohering particles has avery large surface area as compared to the size of the electrode. Thedielectric film conforms to the irregularities of the surface of thecohering metal particles and has a correspondingly large area, thusgiving a condenser embodying such an electrode a much greater capacitythan can be obtained in condensers embodying, for example, electrodescomposed of metal foil. As described in my Patent No. 2,280,789,electrodes may also be provided by depositing the minute metallicparticles on a porous base of woven cloth or the like, such a structureproviding an electrode which is porous throughout and which has a verylarge capacity in comparison with its size.

According to the present invention, I obtain great capacities per unitof volume occupied by the electrode at low cost by using for the basematerial on which the metallic particles are deposited, unwoven layerscomposed of strands of various suitable materials such as natural orsynthetic textile fibers, asbestos fibers, plastic fibers or filaments,fiber glass and wires. The strands may be in the form of fibers, singlefilaments, slivers, rovings, strips, yarns, threads, cords or the like.

curred in the manufacture of cloth base electrodes is eliminated, thestrands being held together by the cohering metallic particlescomprising the conductive layers of the electrodes. One or more layersof parallel strands may be employed, the strands in one layer preferablyextending transversely of the strands in adjacent layers. Where thestrands are in the form of rovings, threads, cords and the like, thestrands in a layer are preferably substantially parallel to each other.Where the strands are in the form of filaments or fibers, they may takerandom directions, but the material is prcferably combecl or carded sothat the fibers or filaments extend generally in the same direction. Thestrands are not matted, felt- In producing such electrodes, the cost ofthe weaving operation ined or woven together prior to the deposition ofthe particles, but are bonded together and given strength by thecohering metallic particles. Whether one or more layers of strands areemployed, the thickness of the electrodes can be maintained at a minimumfor the amount of mate rial used, because of the elimination of thecrossing of the strands found in the ordinary woven fabric. Theelectrodes have ample strength, can be made verythin and flexible, andbecause of their thinness and permeability are highly'efiicient from thestandpoints of power factor and resistance when incorporated incondensers.

Referring now to the drawings which show preferred forms of myinvention, FIGURE 1 illustrates a'dry type electrolytic condenserembodying electrodes made according to myinvention, the condenser beingpartially unrolled to illustrate the inner construction; FIGURE 2illustrates one form of electrode forthe condenser of FIGURE 1; FlGURES3 and 4 are sectional views on an enlarged scale taken as indicated bythe lines 3-3 and 44 of FIGURE 2; FIGURE 5 illustrates one step in theproduction of such electrodes; FIGURE 6 is a plan view of a slightly.modified form of electrode; FIG- URE 7 is a similar plan view of anothermodified form of electrode embodying a paper backing member; FIG- URE 8is a section on an enlarged scale taken along line 8-8 of FIGURE 7;FIGURE 9 is a View of a unitary assembly made up of two electrodes and aseparator; FIGURE l0 is a section on an enlarged scale taken along line1010 of FIGURE 9; FIGURES 11 and 12 illustrate modified terminalconstructions of" my invention; FiGURES 13 and 14 diagrammaticallyillustrate steps in one method of producing electrodes embodying myinvention; and FIGURE 15 diagrammatically illustrates a step in anothermethod of producing electrodes embodying my invention. Throughout thedrawings, like elements are indicated by like referencecharacters. Thedrawings are somewhat diagrammatic, the thickness of the metal layersand of the strands being exaggerated and not necessarily in correctproportion.

As shown in FIGURE 1, electrodes embodying the present invention may beincorporated in a condenser 10 of generally conventional construction inthat it is a condenser of the rolled type embodying two electrodes 11prevented from coming in contact with each other by separators 12composed of porous, absorbent paper or the like; The electrodes areprovided with transversely extending terminals 15 and the electrodes andspacers are impregnated with a suitable pasty film-maintainingelectrolyte, various suitable electrolytes being known to those skilledin the art. The assembly may be rolled into substantially cylindricalform as shown and enclosed in a suitable casing (not shown). If thecondenser is intended for alternate current service, then the metal ofboth electrodes is preferably aluminum, magnesium, tantalum or othersuitable film-forming metal or alloy. -If the condenser is intended fordirect current service, only the anode'need be composed of film-formingmetal; the cathode in such a case can be composed of any metal, whetherfilm-forming or not, which will not contaminate the electrolyte or causecorrosion in the device. For example, the film-forming metals notedabove maybe employed or other metals such as copper may be utilized.

The electrodes 11 in the embodiment shown are sub stantially identicalin construction and as shown in FIG- URE 2, each electrode comprises aplurality of closely spaced substantially parallel strands 18 extendinglongitudinally of the electrode and composed of a non-conductingmaterial which will not contaminate the electrolyte, such as purifiedcotton or other cellulosic filaments, fibers, slivers, rovings, yarns,threads orcords, bundles of rayon or plastic filaments, asbestos fibers3 made into thread or cord, fiber glass, and the like. Preferably, butnot necessarily, one or more Wires 19 composed of the same metal as thecohering layers which form the active surfaces of the electrode aredisposed along with the non-conducting strands to increase theconductivity of the assembled electrode. The wires 19, althoughappearing slightly larger in the drawing, are preferably ofsubstantially the same diameter or thickness as the strands 18 so thatthe completed electrode will be of substantially uniform thicknessthroughout. Strands of a wide range of sizes and spacings may beemployed. For example, threads of the type used in weaving the spacergauze ordinarily incorporated in electrolytic condensers, and with 30'to60 strands per inch of width, may be employed with good results. Also, athin layer of cotton or other staple fibers combed or carded intosubstantial parallelism, or a layer composed of cords made by twistingtogether several threads may.

be employed. The terminal comprises a plurality of wires 22 similar tothe wires 19 extending transversely of the electrode and projectingbeyond one edge of the electrode as shown. The whole assembly iscompleted by the layers 20 and 21 of finely divided minute coheringmetallic particles which provide porous conductive layers of greateffective area as the active surfaces of the electrode.

As shown diagrammatically in FIGURES 3 and 4, the layers 20 and 21surround and conform somewhat in contour to the strands 18 and the wires19, and to the wires 22 making up the terminal 15. Preferably the layersare produced by a spray depositing operation as described in my patentsaforesaid and are from 0.001" to 0.005" in thickness. In the sprayingoperation, the minute particles of metal impinge upon the base materialand against each other while in a molten or plastic state in such mannerthat they adhere firmly to the strands making up the base and the wiresmaking up the terminal and cohere, i.e., become welded, to each other toprovide a unitary conductive structure. While the individual particlesare securely welded to each other, they are not welded throughout theirentire surface areas, but rather the deposited surface is porousthroughout, there being minute passageways, interstices, openings andthe like between the particles, giving the entire structure a porous andabsorbent quality and providing the electrode with a large area of metalexposed to the action of electrolyte when the electrode is incorporatedin a condenser.

In producing electrodes of this type, it is only necessary to lay up thestrands 1'8 and Wires 19 and terminal wires 22 in the manner shown inFIGURE Sand then coat the assembly to produce the layers 20 and 21.While the coating operation is preferably done by spraydepositing asnoted above, other methods for producing the cohering layers of finelydivided metallic particles may be employed. For example, powdered .metalmay be deposited on the assembly of FIGURE 5 and then the, wholesubjected to a sintering operation under conditions of pressure andtemperature which will bond the metallic particles together into porousconductive layers 29 and 21. When the layers are formed by sintering, itis desirable to employ non-combustible materials such as asbestosfibers, fiber glass or wires for the strands 18.

While the strands 18 are preferably composed of fibrous material whichis permeable by the electrolyte, any stranded material which will notcontaminate the condenser may be employed, for example, parallel wirescomposed of film-forming material may be utilized for the electrodeitself, as well as for the terminal member. Terminals other than theparallel wires shown may be employed, foil terminals welded or sprayedto the electrode being satisfactory. Wire terminal members of the typeshown in the drawing may be coated throughout as shown, but only theportion overlying the body of the electrode need be coated to bond theterminal and electrode together. Other suitable terminal constructionsare In FIGURE 6, a modified form of electrode 25 is illustrated. In thisform of electrode, the strands 18, wires 19, terminal wires 22 andconductive layers 24 and 21 may be just as described above, but theelectrode is further reinforced by the provision of a layer of spacedstrands 26 extending substantially at right angles to the strands 1S andwires 19, and preferably composed of the same material as the strands18. The transverse strands 26 are preferably disposed over the strands18 before the metallic layers 25) and 21 are deposited. Thus, thedeposited layers 20 and 21 bind the strands 26 into the electrodestructure, and the strands 26 serve to reinforce and strengthen theelectrode Without increasing its resistance to bending about axestransverse to the electrode. Where thick electrodes of large capacityper unit of area are desired, several layers of parallel strands may beemployed,

the strands in one layer preferably extending transversely of thestrands in adjacent layers.

In FIGURES 7 and 8, a further modification is illustrated in which theelectrode indicated in general at 27 includes strands 18, wires 19 andterminal wires 22 as before, but in this case, the assembly of strandsand Wires is laid upon a sheet 28 of porous material, preferably afelted fibrous material, such as paper, asbestos sheet, felted glassfibers, or the like, suitable for use as a spacer or separator. Theassembly is sprayed or coated from one side only, producingtheconductive layer 3%. This arrangement produces a unitary electrodeand separator assembly, and such a structure can be made into acondenser Without requiring the use of separately formed spacers 12 asrequired in the condenser of FIGURE 1, the sheets 28 of two similarelectrodes 27 functioning as the spacers or separators for thecondenser.

FIGURES 9 and 10 illustrate a still further modification of theinvention in which two electrodes and a separator are incorporated in asingle. assembly indicated at 31. In this construction, one electrodeconsists of the parallel strands 32 and the terminal wires 33 bondedtogether by the cohering conductive layer 3.4, while the other electrodecomprises the parallel strands 35 and terminal Wires 36 bonded togetherby the conductive layer 37, these electrodes being'separated by theporous spacer 38 which may be similar to the spacer 28'. The spacershould be suflicie'ntly porous to permit penetration of the electrolyte,but dense enough to prevent the metal-lie particles making up the layers34 and 37 from coming into contact with each other. This assembly ineffect constitutes two of the electrodes shown in FIGURES 7 and 8produced upon opposite sides of a single separator strip. Such anassembly can be immersed in an electrolyte and form a complete condenserin itself, at least one of the conductive layers being composed of anappropriate film-forming metal as noted above. If desired, anot' erspacer or separator can be employed with such an assembly, and theassembly rolled into conventional cylindrical form, or several suchassemblies can be stacked together, with appropriate separators, to forma flat condenser. The previously described electrodes can also bestacked in flat form with interposed separators to constitutecondensers.

In FIGURE 11 I have shown a modified form of terminal constructionadapted for any of the previously described forms of electrodes. In thisconstruction, the electrodes may be produced in the form of a continuousstrip 39 embodying strands 18 and wires =19 bonded together by thelayers 20 and 21 as in FIGURE 2, but the terminal is produced bysevering the wires 19a, 19b and 19c as at 39a, 39b and 390, pulling themout of the strip 39 and bending them at right angles to the strip toconstitute the terminal 40. It will be noted that the Wires'19a, 19b and19c are preferably severed at different points so that substantially thesame amount of each wire will project beyond the edge of the strip 39 toconstitute the terminal. The strip may be severed, for example, at thepoint indicated by the broken line 42 into separate electrodes,

the strip being of indefinite length and the terminals 40 being providedat appropriate intervals along the strip.

FIGURE 12 illustrates another terminal construction. Here again, theelectrodes may be produced in the form of a strip 39 embodying strands18 and wires 19, but in this modification the terminal memberconstitutes a part of the strip itself, the strip being cut as at 43,and the cut portion folded to extend transversely away from the strip asshown to provide a terminal member 44. As before, the strip 39 may besevered into a plurality of electrodes as indicated by the broken line42, for example, and again the strip 39 may be of indefinite length withthe terminals 44 positioned at appropriate intervals to make electrodesof the desired length and capacity.

Various methods may be employed in producing electrodes according to myinvention. Preferably the methods are arranged so that a series ofelectrodes can be produced by continuous spraying operations, thespraying operations being carried out while the material is in strip orWeb form, the web later being severed into proper length for electrodes.One'such method of producing electrodes such as the electrodes 11described above is illustrated diagrammatically in FIGURES 13 and 14. Asshown in FIGURE 13, a plurality of strands 18 and wires 19 of indefinitelength may be assembled with terminal Wires 22 interwoven transverselyof the strands 18 and wires 19 only sufficiently to hold the terminalwires in position until the conductive layers are produced to bond theterminals and parallel strands together; the

terminals being spaced distances corresponding to the re-v quiredlengths of the electrode. A strip embodying such parallel strands andinterwoven terminal wires may be wound on a drum 45 as shown in FIGURE14, guided by guide rolls 46 and 47 past metallizing guns 48 and 49which are arranged to direct sprays of molten metal on opposite sides ofthe strip and wound again on a takeup drum 50. Thereafter, the electrodematerial can be subjected to a film-forming operation, if the electrodesare intended for use as condenser anodes, and severed into appropriatelengths for electrodes either before or after the film-formingoperation. Electrodesembodying terminals of the types shown in FIGURES11 and 12 are particularly adapted to continuous production by apparatussuch as shown in FIGURE 14, for the reason that the terminals areproduced from the strip itself and the strip can be sprayed or otherwisecoated with metal and subjected to'the filming operation before theterminals are made.

Another method by which a plurality of electrodes may be formed by asingle spraying operation is illustrated in FIGURE 15 in which a drum 57is employed to support the strands 18, wires 19, and transversely ex--tending terminal wires 22. In carrying out this method, the transversewires 22 are positioned on the drum, and the strands 18 and wires 19wound around them. Thereafter, the drum is rotated while themetal'lizing gun 55 is employed to produce the required conductivelayer. After the spraying operation has been completed, the electrodematerial may be severed into appropriate lengths, each including aterminal member 22, and removed from the drum. This type of apparatus isparticularly convenient where it is desired to employ transverse strands26 as shown in FIGURE 6, or where a separator such as the separator 28of FIGURES 7 and 8 is to be used as a backing for the electrode. Themethods described above can be adapted readily to the production ofother types of electrodes embodying the present invention.

In the foregoing description the invention has been described as it maybe applied to electrolytic condensers of the so-called dry type, butthose skilled in the art will appreciate that it is useful in connectionwith other types of condensers, as well as various electrolytic devices.The drawings illustrate electrodes in which parallel strands areemployed, but as noted above parallelism ti ve material constituting aseparator, a layer of unwoven parallel strands extending along one sideof said strip parallel thereto and a porous conductive layer of fine- 1ydivided cohering metallic particles adhering to said strands and stripand bondingsaid strands to each other and to said strip, said .porousconductive layer constituting one electrode, and another layer ofunwoven parallel strands extending along the opposite side of said stripparallel thereto and another porous conductive layer of finely dividedcohering metallic particles adhering to the strands of said other layerand to said opposite side of said strip and bonding the strands of saidother layer to each other and to said strip, said other porousconductive layer constituting another electrode separated from saidfirst electrode by said separator which serves as a barrier to preventthe metallic particles on one side thereof coming in contact with themetallic particles on the other side thereof, and separate terminalmeans for each of said electrodes.

2. An electrolytic condenser comprising an electrode assembly accordingto claim 1 wherein at least one of said porous conductive layers iscomposed of particles of a film-forming metal and is provided with adielectric film, and a film-maintaining electrolyte permeating saidassembly.

3. The method of making electrodes for electrolytic devices whichincludes the steps of providing a base of porous non-conductive materialconstituting a separator, providing a layer of separate unwoven parallelstrands of fibrous material on each side of said base, moving said basewith said layers continuously past metallizing noz zles positioned onopposite sides of the base and spraying finely divided molten metallicparticles from said nozzles into said'layers of strands to coat saidstrands with a porous conductive layer bonding said unwoven strands toeach other and to said base but preventing the metallic particles on oneside of the base to come in contact with the metallic particles on theother side of the base.

4. A flexible permeable unitary laminated metallic conductive stripcomprising at least two unwoven layers of parallel strands, with thestrands of one layer extending transversely of the strands in anadjacent layer and bonded together by coalesced metal particles.

UNITED STATES PATENTS 2,037,848 Brennan Apr. 21, 1936 2,146,029 SchimkusFeb. 7, 1939 2,177,086 Williams Oct. 24, 1939 2,177,819 Booe Oct. 31,1939 2,206,050 Robinson July 2, 1940 2,232,320 Georgiev Feb. 18, 19412,232,484 Shugg Feb. 18, 1941 2,280,789 Brennan Apr. 28, 1942 2,299,228Grey Oct. 20, 1942 2,299,667 Wagerman Oct. 31, 1942 2,310,932 BrennanFeb. 16, 1943 2,375,211 Brennan May 8, 1945 2,407,833 Jablonsky Sept.17, 1945 2,470,826 McMahan May 24, 1949 FOREIGN PATENTS 503,370 GreatBritain Apr. 5, 1939

